Latex paints have gained market share, especially (thought not solely) in respect of architectural coatings, among other things because of environmental concerns with solvent-based paints. This is a consequence of the fact that latex paints exhibit desirable characteristics which are environmentally friendly compared to those of solvent-based paints. However, there are some properties of conventional latex paint and films produced from them that are problematic. For instance, in order to achieve suitable color pigment dispersion in latex paint and precursor colorant compositions therefor, it is typical to incorporate a significant amount of one or more surfactants and/or one or more dispersants. These surfactants and dispersants contain hydrophilic as well as hydrophobic segments or portions for wetting the pigment material (as closed) and dispersing it in the latex paint's aqueous phase. Relatively speaking the amount of surfactants and/or dispersants in deeper-color and clear-base paints is even greater due to the need to tint the paint with a large amount of colorant(s). A paint film produced from latex paint having a significant amount of surfactant- and/or dispersant-content is prone to absorb water unduly, which leads to swelling and softening of the paint film and damage to the film when water on its surface is removed by wiping or the like; this is because the hydrophobic portions of the surfactants and dispersants are not sufficient to override the water-attractive properties of the hydrophilic portions. Additionally, a conventional latex paint film can also be disadvantageous as a consequence of the water affinity of the surfactants and dispersants contained therein because they may leach to the surface of the paint film when it is in contact with water—for example, during water-cleaning thereof—leaving visible water stains on the paint film surface.
A further difficulty encountered with latex paint and films produced therefrom is gloss level impairment. Since gloss level depends on the type and amount of pigment utilized, large amounts of color pigment or extender pigment in colorant compositions can decrease gloss level of a film produced from a latex paint tinted with such colorant composition. Additionally, the incorporation of such pigment may decrease gloss level to a different extent from one color to another. A loss of uniformity exacerbates gloss-level disadvantage.
Moreover, the capacity of latex paint to exhibit good flow and leveling properties to provide a paint film with a smooth finish that is substantially free of brush marks (which is particularly desirable for high gloss paints) can be undercut because of the limitations of various types of thickeners typically utilized in latex paint to achieve desirable flow and leveling characteristics, i.e., a favorable rheology. More specifically, latex paints incorporating associative thickeners such as hydrophobically modified ethylene oxide urethane rheology modifiers (“HEURs”) exhibit good flow/leveling characteristics. Other thickeners, such as cellulose ethers, hydrophobically modified cellulose ethers, alkali soluble or swellable emulsions, and hydrophobically modified alkali soluble or swellable emulsions, can cause the low/leveling characteristics of the paint to depart from an optimal level.
It would be highly advantageous if there were available a latex paint film, as well as a latex paint (and a precursor colorant composition therefor) which produces such paint film, not subject to the water-sensitivity or staining, gloss-impairment, and rheology-change which can characterize conventional latex paint films and paints utilized to produce same, especially deep and clear tint-base paints.